Is your compressor running, but your cold room is still warm? This is a common problem in cold storage. The unit sounds busy, yet the temperature will not drop. The cooling is far weaker than it should be.
Don’t worry. Most cases of a compressor running but not cooling come from a few simple causes. This guide explains each one and shows you how to fix it.
The most common causes are:
- Refrigerant leak
- Frost on the evaporator
- Expansion valve blockage
- Poor cold room door sealing
- Other hidden issues, such as clogged filters or a faulty controller
1. Refrigerant Leak
A refrigerant leak is one of the top reasons a cold room is not cooling. Refrigerant is the “blood” of the system. When it runs low, the system cannot remove heat, and cooling efficiency drops.
What to do:
- Check the refrigerant pressure.
- If the refrigerant is low, recharge it to the normal range.
- Inspect the lines and fittings, find the leak, and repair it.
Recharging alone will not solve the problem. If you do not fix the leak, the refrigerant will escape again.
2. Frost on the Evaporator
Frost on the evaporator blocks air flow and heat exchange. Think of the evaporator covered in a thick layer of ice. It cannot take in heat from the air, so cooling efficiency falls.
What to do:
- Check the evaporator surface. If it is dusty, clean it.
- If frost builds up often, check the defrost settings. These include the defrost cycle, defrost time, and defrost temperature.
- Check the heat transfer tubes and the defrost probe. Make sure they are not damaged.
3. Expansion Valve Blockage
A blocked or badly adjusted expansion valve limits refrigerant flow. This reduces cooling performance. Check that the valve works properly and look for signs of overheating or blockage. You can also check the refrigerant flow. Watch the evaporator pressure and temperature, and look for frost on the suction line.
An expansion valve blockage usually has one of two causes.
Cause A: Dirt in the system
Impurities such as solder slag, copper, and iron filings can clog the valve.
What to do:
- Carefully disassemble and clean the expansion valve. Replace the filter if there is one.
- Reinstall the valve. Make sure the connections are tight and leak-free.
- Recharge the refrigerant and test the system.
Cause B: Ice from moisture
Too much moisture in the system can freeze at the valve and block it.
What to do:
- Defrost the valve naturally, or carefully use a hair dryer.
- Replace the filter drier to prevent future freezing.
4. Poor Cold Room Door Sealing
A good cold room door seal is vital. When the seal is old or damaged, warm outside air leaks in and mixes with the cold air. This lowers cooling efficiency. It also raises power use and increases your electricity bill.
What to do:
- Replace old or damaged door seals right away.
- Choose durable, high-quality materials such as silicone or EPDM rubber.
CRYO provides good quality cold room door. Our technology is from world-famous partners: German Teledoors, and USA Jamison.
5. Other Hidden Causes
Other problems can also cause poor cooling. Clogged filters and a faulty controller are two examples. Regular cold room maintenance and servicing can prevent most of these issues.
FAQ
Why is my compressor running but not cooling?
The most common causes are a refrigerant leak, a frosted evaporator, a blocked expansion valve, and worn door seals.
How do I know if my cold room has a refrigerant leak?
Signs include low refrigerant pressure, weak cooling, and a compressor that runs for long periods. Check the lines and fittings for leaks.
How often should I service my cold room?
Regular servicing helps catch small problems early. Many operators schedule inspections every few months, depending on usage.
Need Help?
If your compressor is running but not cooling, and these steps do not solve it, contact a qualified refrigeration technician. CRYO is an international company with 20+ years of experience in the refrigeration industry, specializing in the design, production, sales, and after-sales service of cold storage solutions. We are providing industry-leading cold room solutions. If your refrigerator evaporator is making unusual noises, take a look at this blog post. If you have any questions, feel free to contact CRYO. Fixing the cause early protects your stock and cuts energy costs.